Buggy code:
public class Fraction extends Number implements Serializable , Comparable < Fraction > , FieldElement < Fraction > { public static final Fraction TWO = new Fraction ( 2 , 1 ) ; public static final Fraction ONE = new Fraction ( 1 , 1 ) ; public static final Fraction ZERO = new Fraction ( 0 , 1 ) ; public static final Fraction FOUR_FIFTHS = new Fraction ( 4 , 5 ) ; public static final Fraction ONE_FIFTH = new Fraction ( 1 , 5 ) ; public static final Fraction ONE_HALF = new Fraction ( 1 , 2 ) ; public static final Fraction ONE_QUARTER = new Fraction ( 1 , 4 ) ; public static final Fraction ONE_THIRD = new Fraction ( 1 , 3 ) ; public static final Fraction THREE_FIFTHS = new Fraction ( 3 , 5 ) ; public static final Fraction THREE_QUARTERS = new Fraction ( 3 , 4 ) ; public static final Fraction TWO_FIFTHS = new Fraction ( 2 , 5 ) ; public static final Fraction TWO_QUARTERS = new Fraction ( 2 , 4 ) ; public static final Fraction TWO_THIRDS = new Fraction ( 2 , 3 ) ; public static final Fraction MINUS_ONE = new Fraction ( ( - 1 ) , 1 ) ; private static final String ZERO_DENOMINATOR_MESSAGE = "zero<seq2seq4repair_space>denominator<seq2seq4repair_space>in<seq2seq4repair_space>fraction<seq2seq4repair_space>{0}//{1}" ; private static final String OVERFLOW_MESSAGE = "overflow<seq2seq4repair_space>in<seq2seq4repair_space>fraction<seq2seq4repair_space>{0}//{1},<seq2seq4repair_space>cannot<seq2seq4repair_space>negate" ; private static final String NULL_FRACTION = "null<seq2seq4repair_space>fraction" ; private static final long serialVersionUID = 3698073679419233275L ; private final int denominator ; private final int numerator ; public Fraction ( double value ) throws FractionConversionException { } public Fraction ( double value , double epsilon , int maxIterations ) throws FractionConversionException { } public Fraction ( double value , int maxDenominator ) throws FractionConversionException { } private Fraction ( double value , double epsilon , int maxDenominator , int maxIterations ) throws FractionConversionException { } public Fraction ( int num ) { } public Fraction ( int num , int den ) { } public Fraction abs ( ) { } public int compareTo ( Fraction object ) { } @ Override public double doubleValue ( ) { } @ Override public boolean equals ( Object other ) { } @ Override public float floatValue ( ) { } public int getDenominator ( ) { } public int getNumerator ( ) { } @ Override public int hashCode ( ) { <START_BUG> return ( 37 * ( ( 37 * 17 ) + ( getNumerator ( ) ) ) ) + ( getDenominator ( ) ) ; <END_BUG> } @ Override public int intValue ( ) { } @ Override public long longValue ( ) { } public Fraction negate ( ) { } public Fraction reciprocal ( ) { } public Fraction add ( Fraction fraction ) { } public Fraction add ( final int i ) { } public Fraction subtract ( Fraction fraction ) { } public Fraction subtract ( final int i ) { } private Fraction addSub ( Fraction fraction , boolean isAdd ) { } public Fraction multiply ( Fraction fraction ) { } public Fraction multiply ( final int i ) { } public Fraction divide ( Fraction fraction ) { } public Fraction divide ( final int i ) { } public static Fraction getReducedFraction ( int numerator , int denominator ) { } @ Override public String toString ( ) { } public FractionField getField ( ) { } }

Fix:
return ( 37 * ( ( 37 * 17 ) + ( numerator ) ) ) + ( denominator ) ;